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 Form 4 Physics online lessons on thin lenses

Uses of lenses on optical devices

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Uses of lenses on optical devices
Simple microscope– it is also referred to as magnifying glass where the image appears clearest at about 25 cm from the eye. This distance is
known as the least distance of distinct vision (D) or near vision.
Magnification in a simple microscope Magnification produced depends on the focal length of the lens. Lens of short focal give greater magnification than those of long focal length. The angle #beta# subtended by the image at the eye is
much greater than #alpha# which is the angle that the object would subtend at the eye when viewed without the lens. The ratio of the #beta# to #alpha# is known as angular magnification or magnifying power of an instrument. The angular magnification is equal to linear magnification.